In 3GPP (3rd Generation Partnership Project), which is a project aiming to standardize a mobile communication system, a technology for selecting a target cell used as a serving cell from a plurality of cells operated at different frequencies is proposed.
Specifically, a user terminal measures, if a start condition is satisfied, a quality of a neighboring cell adjacent to the current serving cell, and selects, from the cells that satisfy selection conditions, the target cell used as the serving cell.